Consistency between Calculated and Tested Values of Critical Flutter Speed of Flat Box Girder

To obtain the precise flutter performance of a flat box girder, concordances between calculated values and tested values of critical flutter speed were studied, using sectional model wind tunnel testing combined with the calculation method of critical flutter speed. The flutter derivatives under different wind attacks of the box girder were obtained using forced vibration tests. The critical flutter speeds were then calculated using the bimodal coupled flutter analysis method. Finally, the critical flutter velocities were obtained via the sectional model tests under the same conditions. The results indicate that the differences between calculated and tested critical speeds in all cases are minor, and the percent errors are less than 5% when the attack angle is 0°. The differences between calculated and tested critical speeds are substantial when the attack angles are 3° and 5°, and the percent error can reach 10.4%. Based on a comparison of flutter factors derived from the calculation and the test, excluding the effect of nonlinear aerodynamic force and structural damping, it is conjectured that the differences may have been induced by variation in flutter derivatives caused by different coupled motions.